Heretofore, the voice information for cinema for a movie theater is recorded on the sound track provided on a right or left edge of a picture area of the cinefilm along the film running direction.
If a light source other than a laser source, such as an LED array or a halogen lamp, is employed, the output is low, sufficient luminosity cannot be achieved, and a lot of time is consumed in recording the information. However, if the usual laser beam is employed, a speckled noise is produced in an ultimate image thus seriously deteriorating the image-forming performance. The information concerning the speckled noise may be found in "Introduction to Fourier Optics", pages 131 to 134, by Joseph W. Goodman, McGrow-Hill Book Company, 1968. On the other hand, with the coherent laser beam, the cut-off of the resolution for the spatial frequency is also reduced by one half. Consequently, a light source other than the laser light has so far been employed in the optical recording system. However, if the light source employed is of the type in which a spatial modulator is based on the polarized light produced under e.g. the electro-optical effect, it is necessary to provide polarizing plates ahead and at the back of the modulator, which detracts from the efficiency since the system is used in conjunction with a non-polarized light.
Meanwhile, for recording the information without voids, such as by a printer, the conventional practice has been to employ two staggered arrays of modulators. If a light source of a lower light output is employed for affording a homogeneous illumination on these staggered rows of modulators, it has been necessary to provide a plurality of light sources.
It is noted that the following apparatus may be contemplated as a technology of recording the digital voice on the cinefilm.
That is, the device for digital recording of the voice information includes a light source 11, made up of a plurality of light-emitting diodes 10 or halogen lamps, a first polarizing plate 12 for polarizing the light radiated from the light source 11 for re-radiating the light, a light modulator 13 for polarizing the information light in a pre-set manner for re-radiating the light and a converging lens 15 for converging the information light from the second polarizing plate 14 for directing the converged light to a sound track 16a of a cinefilm 16, as shown in FIG. 1.
The light modulator 13 has a first line of apertures or through-holes 17 and a second line of apertures or through-holes 18, each line 17 and 18 having ten apertures or through-holes 17a to 17j and 18a to 18j, respectively. The apertures 17a to 17j of the first aperture line 17 and the apertures 18a to 18j of the second aperture line 18 are positioned so that a land equal to one-aperture width is left between the neighboring apertures. Besides, the apertures 18a to 18j of the second aperture line 18 are disposed directly below the lands between the apertures of the first aperture line 17. That is, the apertures 17a to 17j of the first aperture line 17 are placed in a staggered relation with respect to the apertures 18a to 18j of the first aperture line 18.
With the above-described information recording apparatus, when the recording of the voice information is started, the cinefilm starts to be taken up, at the same time that the light-emitting diodes 10 are illuminated to radiate the light from the light source 11. This light is radiated on the polarizing plate 12.
Since this radiated light is the natural light, the first polarizing plate 12 translates the radiated light into a linearly polarized light which is then radiated to the apertures 17a to 17j and 18a to 18j of the light modulator 13.
The light modulator 13 is driven responsive to the voice information entered via an input terminal 19 to modulate the direction of polarization of the linearly polarized light transmitted through the apertures 17a to 17j and 18a to 18j under the so-called electro-optical effect for translating the voice information in the form of electrical signals into signals in the form of the directions of spatial polarization which are then radiated on the second polarizing plate 14.
The second polarizing plate 14 translates the non-polarized light component, generated by the modulation of the direction of polarization by the modulator 13, into the linearly polarized light, which is then radiated on the converging lens 15.
The converging lens 15 converges and radiates both the linearly polarized light from the apertures 17a to 17j of the first aperture line 17, which has been converted into signals of the spatial light intensity, and the linearly polarized light from the apertures 18a to 18j of the second aperture line 18, which has similarly been converted into signals of the spatial light intensity, on the sound track 16a of the cinefilm 16.
The cinefilm 16 starts to be taken up when the recording of the voice information is started as described above. The apertures 17a to 17j of the first aperture line 17 and the apertures 18a to 18j of the second aperture line 18 are arrayed in a staggered relation to each other. Consequently, the entire voice information is recorded on the sound track 16a in such a manner that the voice information recorded by the linearly polarized light from the apertures 18a to 18j of the second aperture line 18 is stuffed in the void areas between the voice information recorded by the linearly polarized light from the apertures 17a to 17j of the second aperture line 17. That is, the voice information recorded by the linearly polarized light from the apertures 17a to 17j of the first aperture line 17 and the voice information recorded by the linearly polarized light from the apertures 18a to 18j of the second aperture line 18 are alternately recorded on one and the same line on the sound track 16a.
In this manner, a row of the voice information is recorded without gaps in the sound track.
However, since an array of LEDs or a halogen lamp is employed as a light source in the above-described conventional information recording device, an output of the light source is low, a sufficient luminosity cannot be developed, and a lot of time is consumed in recording the voice information.
Besides, since the LED array or the halogen lamp is employed as the light source in the above-described information recording device, it is necessary to provide polarizing plates ahead and at the back of the light modulator 13 for translating the non-polarized light into the linearly polarized light in recording the voice information, with the result that the number of components, such as the first and second polarizing plates 12, 14, is increased and the structure becomes complicated to raise production costs.
On the other hand, the use of the first and second polarizing plates 12, 14 for polarization may be said to be responsible at least partially for the low light output of the light source and insufficient luminosity.
In addition, with the above-described recording of the voice information in which the voice information is recorded without voids or gaps using the light modulator 13 having the apertures 17a to 17j of the first aperture line 17 and the apertures 18a to 18j of the second aperture line 18 arranged in a staggered relation to each other, it is necessary to provide a plurality of light sources 51 for uniformly irradiating the aperture lines 17, 18 with the light from the light source, with the result that again the number of components, such as the first and second polarizing plates 12, 14, is increased and the structure becomes complicated to raise production costs.
For overcoming the above-described inconveniences, a semiconductor laser light capable of outputting a laser light beam as a linearly polarized light of higher luminosity may be employed as the light source. However, if a laser beam is radiated on the sound track 16a of the cinefilm 16 using a conventional semiconductor laser, the speckled noise is incurred when the voice is recorded on the sound track 16a of the cinefilm 16. Besides, the cut-off of the resolution of the spatial frequency is decreased by about one half with the coherent laser light beam radiated from the semiconductor laser.
In view of the above-depicted inconveniences of the prior art, it is a principal object of the present invention to provide a method and apparatus for recording the information in which the recording may be made in a shorter time and at low cost by a simplified arrangement employing a smaller number of component parts such as the polarizing plates and in which, even with the use of the light modulator provided with plural aperture lines, these aperture lines may be irradiated uniformly by the radiated light.